How many layers of cotton yarn should be covered when the temperature is above 25 degrees in summer?

Two floors.

Double-layer thickness sleeping bags are most suitable for summer when it is warm and then cold. The average indoor temperature is between 24 and 27 degrees Celsius. Be sure to choose a sleeping bag that is moisture-absorbent and breathable, especially when children sleep on their backs, which are prone to sweating and are light and thin. The fabric helps to wick away sweat and dissipate heat, so it is especially suitable to choose a sleeping bag made of bamboo fiber or modal, which has a cool feel.